Mechanical stoker



Dec. 8, `1925- R. A. FoR'EsMAN MECHANICAL STOKER ATTORNEY Dec. 8, l925 R. A. FORESMAN MECHANI CAL STOKER wlTNEssEs; #E

ATTORNEY Patented Dec. 8, 1925.

UNITED STATES PATENT OFFICE.'

RQBERT A. FOBESMAN, F ESSINGTON, PENNSYLVANIA, ASSIGNOR T0 WES'lIIiI'G` HOUSE ELECTRIC & MANUFACTURING' COMPANY, A. COBPOBATICN 0F PENNSYL- VANIA.

' MECHANICAL STOKEB.

Application led June 22, 1920. Serial No. 390,855.

To all lwhom z't may cof/wem.' l duce a stoker wherein the fuel is supplied 50 Be it known that I, ROBERT A. onnsinnrrf a citizen of the United States, and a resident of Essington, in the county of Delaware and I State of Pennsylvania, have invented a new and useful Improvement in Mechanical Stokers, of which the following is a. specification.

This invention ,relates to mechanical stokers, and more part cularly to stokers of the underfee'd type in which the fuel is supplied to an inclined overfeed grate at a point near the front and therefuse therefrom discharged at a point near the rear of the grate. A

The object of my invention is the production of a simple and comparatively inexpensive stoker construction which opere ates efficiently and economically andwhich employs a minimum number of moving elements, thereby reducing the power required for its operation and the cost of` maintenance.

In furnaces of the usual overfeed type 'the grate bars extend across the furnace in parallel relation and from the front coal receiving end of the furnace to the rear ash discharging end thereof, and arel inclined from the front to the rear of the furnace.A The 10 bars are usually reciprocated by an engine disposed at the front vof the furnace for the,

purpose of radually shak ng downand agitating the iel so that fuel supplied to the grate near the upper end thereof is caused '5 to gravitate toward the bottom of the grate from whence the refuse is discharged into a pit 'adjacent the lower end ofthe grate. Grate bars of this type must necessarily be made of heavy material in order to with- -0 stand the load imposed thereon and the high temperatures to which they are exposed, and

consequently considerable energy is `absorbedl in movng the heavy bars loaded with fuel over the bearings which, on account of the 5 excessive heat, are impracticable to lubricate. The wear of the bars and bearings is consequently excessive, and as a result thereof, such parts must be frequenfly renewed.

It is an object of this invention to proto the grate uniformly throughout the width of the furnaoe'and d stributed and advanced to the ash pit in such manner that ecient combustion is maintained..

A further object of the invention is to produce a furnace having the above characteristics of performance which ma be actuated with a minimum of power an has a minimum number of movng elements com-1 pared with stokersof the same capacity and having moving grate bars. l e

Another object is to produce a stokcr wherein the grate bars or tuyres are stas tionaryand are arranged in transverserows across the entire width of the furnace, and wherein the fuel is agitated and advanced by means of pivoted sectors adapted to be operated in recesses between the grate bars.

These and` other objects which will be made apparentl throughout the further desorption of the invention are attained in the stokerembodying the features illustrated in the accompanying drawings wherein:

Fig. 1 is a longitudinal sectionthrough a furnace Stoker embodying features of my invention, and Fig. 2 is a plan view of the stoker illustrated in I"v g. 1. c y y Referring to the drawings, the furnace includes a front wall5, a reartwalll 6, and side walls 7 forming a rectangular space in which the stoking mechanism is located. The fuel supporting grate includes, as shown, lthree, separate transverse sections 8, 9, and 10 disposed one beneath the other in different parallel planes in such manner as to prov de recesses 11 and 12 between the adjacent sections. lEach grate section comprises three separate groups of rectangular'tuyre blocks 13 mounted upon stepped tuyre supporting frames 14 which in turn are supported upon the main grate supporting frame disposed beneath the grate sections in a manner to be hereinafter described. The'tuyres of each section are crowned by locking tuyres 16 which, in the case of the'top'section 8., are secured to the rear wall 17 of the fuel retort 18 by means of bolts 19; The lockng tuyres '16 of the center section 9 and the rear section 21 which form bottom closures for the re The casting is supported upon transverse angle ironsA 22 which extend across the v furnace and are secured at intervals to ver- I eo tical beams 22 which in turn aresupported upon the frame disposed beneath the grate sections. The casting 21 is supported upon a transverse I-beam 23 which forms apart of the said frame.

Fuel is supplied to the grate sectionsbyl means of a pair of rams 24 mounted beneath the discharge openings 25 of the supply hoppers 26 and adapted to be reciprocated forward andl rearward by means of suitable engines or motors 27. Each ram is rectangular in shape and operates ina guide slot 28 formed beneath the hopper 26, and is ada 3ted to force fuel passing through the ischarge openings 25 through the inlet 29 of the retort 18 in a well known manner. However, the retorts employed in the present em'- bodiment of the invention are 4provided with discharge openings of such width that, when placed sideV by side, they serve to provide a fuel retort extending entirely across the front of the furnace from which coal is uniformly discharged on to the grate sections along their entire width.

As the plungers 24 continue to force fuel into the retort, the fuel gravitates over the uppermost grate section 8 and falls into the recess 11. Beneath the lowermost tuyre 13 of the upper section8, an agitator sector or fuel moving member 30 is pivoted at 31 to -a support 32 carried by the casting 20. This agitator or fuel moving member is p-rovided with a series of tuyre blocks 33 through which air from the air box 34 located be-l neath the grate sections may pass, and the lower end of the agitator is provided, with a shoe 35 adapted to move over the concave surface 36 of the casting 20 in close proximity thereto so asto provide a close sliding jointthrough which the :fuel cannot readily ass.

The agitator 30 is' adapted to be oscillated so as' toI swing` upward and rearward out of the recess 11 into the position similar to that in which the lower agitator 37 in the recess 12 is shown. rlhe agitator 37 isin every particular identical to the agitator 30 and will not therefore be ydescribed in detail.

Fuel falling into the recess 11 from the grate section 8 is forced upwardfand rearyward bythe rearward swing of the agitator 30, and is moved on to the central grate s ection 9 from whence it falls into the recess 12 and into contact with the swinging agitator the final or lowermost grate section 10, from whence it is discharged on to the dump grate 38. The grate may be of any suitable construction s uch as that illustrated.

The a 'tato'rs 30 vand 37 are adapted to be oscillate by the reciprocatory movement of the plunger andare connected thereto by operating mechanism which includes a lever 39 pivotally mounted'for oscillation upon a bracket 40 secured, to the transverse retort supporting channel frame 41. The upper end of thls lever is slidably connected at 42 to the ram 24 while the lower end is slidably connected at' 43 to a connectin rod 44 which extends rearwardly and whic is supported at its forward end in a bracket 45 secured to. the frame 41 and at its rearward `end in a bracket 46 carried by the beam 22. The agitators 30 and 37 are each provided witha forwardly extending lug 47 to which ends of the links 48 and 49 respectively are pivotally connected. The other ends. of the said links are pivotally connected to oscillating levers 50 and 51) respectively. yThe lever 50 is pivoted at a point 52 intermediate its ends to a bracket 53 carried by the angle irons 22, and its lower end is pivotally connected to the connecting rod 44 by means of a slot and pin connection 54.

The lower end of the lever 51 is pivotally connected at 56 to a bracket 57 secured to the I-beam 23 and is pivotally connected to the rear end of the connecting rod 44 by means of a link 58. It will be seen from the foregoing that rearward movement of the connectin@ rod44 will cause'the agitator 30 to swing xforwardly into the recess and away vfrom the fuel bed, while at the same time the agitator 37 is caused to swing rearwardlyA out of the recess to the fuel bed. The agitators, therefore, operate at all times in opposite directions, and while the upperv.most agitator is forcing fuel onto thefcentral grate section, .the lowermost agitator is moving into the recess to receive fuel forced off the grate section. tion of the agitators just described insures a uniform distribution of the fuel throughout the width of the furnace and a. gradual progressive movement of the fuel toward the dump grate 38.

Because of the effective agitation of thc '.fuel intermediate the ends of the grate surface,the thickness of the fuel bed is maintained practically constant during the operation of the Stoker. Therefore, the danger of forming blow holes through which execs-f1.V A v sive quantities of air may` flow is eliminated. The tuyre 14 and locking tuyre 16 are pro` vided with air passages through which air from the air box beneath the grates may flow to the fuel bed.

ln the construction illustrated it will be seen that the grate sections 8, 9, and 10 ei; tend from one side wall 7 to the other and are made in three transversely alined por-y tions. 'lwo retorts 18. having their com` bined discharee opening extending substantially across the width ofthe furnace and The cooperaserved by two fuel hoppers 26 and two rams 24 supply fuel uniformly across the width of the furnace, and the uniform distribution ofthe fuel is maintained-by the agitators throughout the length and width of the ate surface.

The fuel agitators are the only moving parts in contact with the fuel upon the grates, and because of their pivoted bearings Ioffer less resistance to movement than rams and grates having sliding engagement with unlubricated surfaces. The construction `is simple, and the under structure is t moved toward the rear of the furnace.

such that it may readily be fabricated from commercial steel shapes,thereby eliminating the use of heavy castings which are objectionable becauseY they frequently warp due to temperature variations. l ,l

While I have described and illustrated but one embodiment of my invention,- it will be apparent to those skilled in the art that various chan es, modifications, substitutions, additions an omissions may be made in the apparatus illustrated wit-hout departing from the spirit and scope of the invention as set forth by the appended claims.

What I claim is 1. In furnace Stoker, a longitudinal overfeed grate unit having a plurality of`fixed inclined sections spaced to provide a'recess between adjacent sections, means for supaplying fuel to the overfeed grate, and a fuel .movin member pivotallyv mounted in said between adjacent sections and adaptedl to be oscillated toward the front and rear recess inclined sections spaced ,to providea recess j between adjacent sections, means for supplying fuel to the overfeed grate, and a fuel moving-member'suspended within said recess between adjacent sections upon a pivot having its axis disposed transversely of the furnace, said fuel moving member adapted to swingrearwardly and forwardly whereby fuel in contact therewith is agitated and 3. In a furnace stoker, the combination of a longitudinal inclined grate unit, having a plurality of fixed inclined sections spaced Vto provide a recess between adjacent sections, of a fuel moving member pivotally mounted in said recess between adjacent sections for oscillatory movement toward and from the rear of the furnace adapted to receive fuel from one section and move it onto an adjacent section toward the rear of the furnace.

4. In a furnace Stoker, the combination with an inclined grate having a declined stepped series of fixed inclined sections spaced to provide recesses between adjacent sections and adapted to receive fuel at its uppermost section and discharge refuse at itslowermost section, of fuel moving members, pivotally mounted in the recesses between adjacent sections for oscillatory movement toward and from the discharge end of the grate and each adapted to receive fuel from an upper section and move it toward the discharge end of a lower section.

5. In a furnace stoker, a longitudinal overfeed grate unit having a stepped series of fixed inclined sections spaced to provide a recessl Abet-Ween adjacent sections, reciprocating means for supplying fuel to theoverfeed grate, a fuel moving member pivotally mounted in said recess between two adjacent sections and adapted to be oscillated toward and from the discharge end of the grate, and'means connecting the said fuel moving member with the said reciprocating means whereby the said member is oscillated by movement of the reciprocating mean's.

6. In a furnace Stoker, an inclined overfeed grate havingaplurality of fixedlinclined sections spaced to provide recesses between adjacent sections, reciprocating means for supplying fuel to the overfeed grate, a plurality of fuel'moving members pivotally mounted in the recesses between adjacent ated toward and driving means for oscillating the members in one recess forwardly and in 'an aldjacent recessrearwardly by a single move ment of the reciprocating means.

7. In a furnace Stoker, an inclined overfeed grate having a plurality of fixed inclined sections spaced to provide recesses between adjacent sections, means for supplying fuel to the overfeed grate, a plurality of .fuel moving members ivotally mounted in the recesses between adjacent sections extending transversely of the furnace and adapted to be oscillated toward and from the discharge yend of the grate, and driving means connecting the said members for swinging the members in any recess in one direction while the members in an adjacent 'beneath the portion of the grate 'section which forms the upper boundary of the reof the furcess and adapted to oscillate so that the lower end of the member mayswing forwardly into the recess andthereby permit fuel to fall from the portion ofthe grate section above the recess into the said recess, and may swing upwardly and toward the discharge or rear end of the grate and outv of the recess, thereby moving fuel discharged from the sectionabove the recess to the section'l below the recess, and a closure means y ,for thebottom of the recess adapted to `revent the escape of fuel from between the ttom of the said member and the portion of the grate which forms the lower boundary of the said recess. A

9. In a furnace stoker, a longitudinal inclined overfeed grate unit having at 'least two fixed inclined sections extending substantially across the furnace and provided with a transversely disposed recess between adjacent sections extending substantially the entire width of the said grate, means for feeding fuel to `one section from apoint above the said recess', and a fuel moving member extending substantially the entire length of the recess pivotally mounted within the recess so that the lower end of the said member may be swung out of the said recess for the purpose of moving the fuel toward the discharge end of the grate.

10. In a furnace stoker, a plurality of inclined grate sections arranged in an inclined series in dierent substantially parallel planes and spaced apart so as to provide recesses between adjacent sections, and fuel moving members pivotally mounted within the recesses adapted to be swung rearwardly for moving fuel entering the recesses onto the grate sections beneath.

11. In a furnace stoker, an underfeedJetort section extending transversely at the front of the stoker substantially the width of the furnace, an overfeed grate at the rear thereof having a stepped series of fixed inclined sections, said sections being spaced apart to provide recesses between adjacent sections, reciprocating means for underfeeding fuel into said retort in a sheet or layer of substantially the width of the furnace, and thence to the overfeed section through-` out its width, and fuel moving members pivotally mounted within the the recesses ada-pted to be swung rearwardly for moving fuel entering the recesses onto the grate sections beneath.

12. In a furnace stoker, an underfeed retort section extending transversely at the front of the stoker substantially the width of the furnace, an overfeed grate at the rear thereof having a stepped series of fixed inclined sections, said sectionsbeing spaced apart to provide recesses therebetween extending substantially the entire width of the furnace, reciprocating means for underfeeding fuel into said retort in a sheet or layer of substantially the width of the furnace, and thence to the overfeed section throughout its width, and fuel moving members ex-' front of the Stoker substantially the width of the furnace, an overfeed grate at the rear thereof having a' stepped series of fixed inclined sections spaced to provide a recess between adjacent sections, reciprocating means for underfeeding fuel into said retort in a sheet or layer of substantially the width of the furnace, and thence. to the overfeed section throughout its width, fuel moving members pivotally mounted in the recess formed between adjacent sections and adapted to be oscillated toward and from the discharge end of the grate, and means connecting the said fuel moving members with the said reciprocatin means whereby the ysaid members are osci lated by movement of the reciprocating means.

14. In a furnace Stoker, an underfeed retort section extending transversely at the front of the Stoker substantially the width of the furnace, anloverfeed grate at the rear thereof and having a stepped series of fixed inclined sections, said sections being spaced apart to provide recesses therebetween extending substantially the entire width ofthe furnace, reciprocatmg means for underfeeding fuel into said retort in a sheet or layerl of substantially the width of the furnace, and thence to the overfeed'grate throughout its width, fuel moving members extending substantially the length of and pivotally mounted within the recesses and adapted to be swung in and out of the recesses for the purpose of moving fuel toward the discharge end of they grate, and means connecting the said fuel moving members with the said reciprocating means whereby the said member is oscillated by movement of the reciprocating means.

In testimony whereof, I have hereunto ica subscribed my name this 17th day of June,

sonner a. ronnsrran. 

